A function relay is known from DE 10 2004 045 205 A1. The known function relay has a bistable relay structure and a reset structure in a common housing, and can be mounted on a printed circuit board by way of a number of contact pins, which project out of the housing. The reset structure includes a switching lever, which corresponds with the relay structure, and an operating element which can be manually deflected elastically against spring pressure and acts via a driver on the switching lever in such a manner that, when the operating element is operated, the switching lever is moved to a reset position which corresponds with the switched-on position of the printed circuit board relay module. The operating element and the switching lever are in this case guided in the housing in such a manner that the driver is mechanically decoupled from the switching lever in a rest position and in an operating position of the operating element.
A thermal overload relay with contact pins for mounting on a printed circuit board is also known from EP 0 940 831 A2.
Electronic overload relays with their own supply are normally used for protection of an electric motor against overloading. For this purpose, the overload relay is in general connected directly downstream from a switching element associated with the motor, in particular a contactor, in the motor output from an electrical supply network. In the event of a fault, that is to say in the event of overloading, the contactor is disconnected by the overload relay, and is thus automatically isolated from the electrical power supply.
Conventionally, after disconnection, an overload relay is mechanically reset to a switched-on state again, in particular by operation of a reset button. Alternatively, electrical resetting by way of a so-called auto reset can be provided for an overload relay. The electrical energy which is required for the auto reset is initially stored in a capacitor associated with the overload relay, and is available after disconnection for resetting of the relay.
A conventional overload relay generally has a magnetic circuit with a switching rocker fitted with permanent magnets. The magnetic circuit can be electromagnetically excited by a coil, so that the switching rocker moves in a bistable manner from a switched-on position to a switched-off position under the influence of an electrical pulse, and appropriate switching contacts of the overload relay are operated during this process. A corresponding mechanical design is generally integrated in the overload relay, for manual resetting of the relay.
As an alternative to the overload switching described above, a function relay can also carry out another protection or monitoring function, depending on the nature of associated control electronics. In the above sense, a function relay may, in particular, also be in the form of an undervoltage release, temperature monitor, a filling level sensor, etc.